That having said, I quickly checked a few of your games and I think you might study the wrong thing atm. If you want I can have a closer look and zoom for an hour to see if we can tackle it.
Help me understand how I became "stupid"

That having said, I quickly checked a few of your games and I think you might study the wrong thing atm. If you want I can have a closer look and zoom for an hour to see if we can tackle it.
Please help me, I liked chess a lot, but now it drives me into desperation, and I can't figure out why!
Long story short: I have been learning chess a lot during the past several months. I read a very good book, explaining openings, mid games and end games. I also watch GothemChess on a regular bases and learn from him several useful openings.
So far, my hardship payed off: I had a steady climb to about 750 in a couple of days, so I guess I did something right.
Since then, I feel like I lost half of my brain, for I constantly loosing. I feel back under 600, and I commit very stupid mistakes, like suddenly forgetting that pawns eat diagonally, and putting my queen exactly next to one!!!
I am only 34, I don't have any brain issues, and I don't consume anything that might affect my brain. I still have the same board awareness (for better or worse, but I DID manage somehow to reach 750, after all), I constantly re-watch Levy's videos, to catch any small details I might have missed, but I stopped improving. I make even more silly mistakes, blunders or being completely lost in my plan.
I like chess a lot. I felt that a whole world was opened to me once I started learning it seriously, beyond the basic movements I was being taught as a kid. But now I feel absolutely desperate.